As is well known in the trolley vehicle art, an electrically powered trolley vehicle receives the energy needed for its operation from an overhead catenary or a similar power conduit. Mounted atop the trolley vehicle is a trolley pole to which is attached at one end an energy collector assembly. The energy collector assembly rides along the power conduit, or "trolley line" as it is often called, as the trolley vehicle travels along its route of travel. The energy is conveyed from the power conduit through the energy collector assembly of the trolley pole and ultimately delivered to a propulsion unit and other energy consuming devices located on the trolley vehicle.
Also well known in the trolley vehicle art is the operation of a trolley pole switch mechanism (hereinafter "trolley pole switch"). A trolley pole switch is a device situated at a junction of diverging power conduits located above the point where the routes of travel of the trolley vehicle diverge in different directions. The trolley pole switch is used to switch the path of travel that the energy collector assembly of the trolley pole takes at a junction of diverging power conduits. A junction of diverging power conduits may consist of one power conduit strung in a straight path and another power conduit diverging therefrom strung in a path heading to a generally left direction. Likewise, such a junction may consist of one power conduit strung in a straight path and another diverging therefrom strung in a path heading to a generally right direction.
As a trolley vehicle approaches a junction, the trolley pole switch may be commanded to switch the path that the energy collector assembly will travel from the power conduit strung in a straight path to either of the power conduits strung in the left or right direction. When the trolley vehicle seeks to proceed through a junction in a straight path, the trolley pole switch, as explained below, may or may not have to be commanded to switch the path to assure that the energy collector proceeds therethrough on the power conduit strung in the straight path. The route of travel of the trolley vehicle, of course, always corresponds to the path of travel that the energy collector assembly follows through trolley pole switch and thereafter on the power conduit to which it is directed.
The typical trolley pole switch has two switching elements, or "frogs" as they are often called. A frog of the type that is controllable by the instant invention is described in U.S. Pat. No. 5,390,772 to Ta et al., incorporated herein by reference. Each frog, as described in Ta et al., of the typical trolley pole switch, contains an electrical operator such as a solenoid. When the solenoid of one frog is energized, it acts upon certain elements within that frog to switch the path that the energy collector assembly will travel through that frog from the straight power conduit to one power conduit diverging from the straight power conduit. Likewise, when the solenoid of the other frog is energized, it acts to switch the path that the energy collector assembly will travel through that frog from the straight power conduit to another power conduit diverging from the straight power conduit. Still referring to the one-solenoid frog described in U.S. Pat. No. 5,390,772, as the energy collector assembly rides through that frog, it engages a deflector arm which mechanically resets the frog to permit travel therethrough in a straight path. Consequently, the next trolley vehicle that wishes to proceed through that frog on the straight power conduit may do so without the need for any switching of the path.
Various other frogs are configured so that, when the solenoid is energized, the energy collector assembly will travel straight through that frog on the straight power conduit. The energy collector assembly, as it rides through this type of frog, then engages the deflector arm which mechanically resets the frog to permit travel therethrough from the straight power conduit to a left or right diverging power conduit. The next trolley vehicle that wishes to proceed through the frog on the straight power conduit must then energize the solenoid to switch the path.
Certain other types of frogs, however, do not reset mechanically and must be reset via a separate solenoid. These types of frogs thus contain two solenoids. When one solenoid of the two-solenoid frog is energized, it acts to switch the path that the energy collector assembly will travel from the straight power conduit to one of the power conduits diverging therefrom. When the other solenoid of the two-solenoid frog is energized, it acts to switch the path that the energy collector assembly will travel back to the straight power conduit. Consequently, the next trolley vehicle that wishes to proceed through the two-solenoid frog may be required to switch the path so as to assure it will proceed in the direction it intends. The instant invention is capable of controlling the operation of a trolley pole switch no matter which of the aforementioned types of frog(s) is utilized at a given junction of diverging power conduits.
The trolley pole switch alters the path of travel that the energy collector assembly takes therethrough in response to commands received from a controller unit. As described in greater detail in the ensuing paragraphs, the controller unit controls the operation of the trolley pole switch by energizing the frog solenoids. Located in proximity to the trolley pole switch, the controller unit receives signals from a transmitter disposed on a trolley vehicle. The transmitted signals are indicative of a request for the energy collector assembly to proceed through the trolley pole switch in a straight path or veer through it onto either a right path or a left path. The transmitted signals are frequency modulated having resting frequencies centered at 9.2 kHz for a left turn, 11.5 kHz to proceed straight, and 14.0 kHz for a right turn. As a trolley vehicle approaches a junction of diverging power conduits, an operator aboard the trolley vehicle chooses the route of travel that the trolley vehicle is to take at the upcoming junction. The route of travel is chosen via levers or like implements, located in a cab of the trolley vehicle, through which the left, the right or the straight path through the junction may be selected. When a particular route of travel is chosen and its corresponding implement manipulated, the transmitter on the trolley vehicle transmits the appropriate signal to the controller unit. The controller unit receives the signal and generates in response thereto a signal to energize the appropriate solenoid on the trolley pole switch situated at the upcoming junction. The solenoid then acts upon certain elements of the frog to switch the path that the energy collector assembly will take through the trolley pole switch. The trolley vehicle then proceeds through the junction on its chosen route of travel.
Trolley pole switch controller units have been in widespread use in the transit industry for several years prior to the present invention. The typical controller unit includes a radio control board and usually a power supply board. The radio control board includes circuitry for receiving and processing the incoming modulated signals so as to generate intermediate command signals each of which indicative of a command to supply power to an appropriate frog solenoid. The power supply board includes power circuitry for stepping down voltage so as to supply the radio control board with power as well as to supply power to the frog solenoids. In response to each of the three command signals received from the radio control board, the current is switched by an appropriate transistor so that trolley line voltage passes from the power conduit to energize the appropriate solenoid. The solenoid then compels the certain frog elements to switch the path that the energy collector assembly will take through the trolley pole switch.
For those certain prior art controller units that do not include a power supply board, the controller unit includes only the radio board and accompanying power supply circuitry for stepping down voltage so as to supply the radio control board with power. The radio control board still includes circuitry for receiving and processing the incoming modulated signals so as to generate the intermediate command signals. The intermediate command signals, though, are used to drive separate high voltage capacity mechanical relays directly. These relays when actuated directly pass the high voltage of the trolley line to energize the appropriate solenoid of the intended frog. The solenoid then compels the certain frog elements to switch the path that the energy collector assembly will take through the trolley pole switch.
The prior art controller unit contains old technology and therefore exhibits the disadvantages inherent to that technology. Experience has shown that the prior art controller unit oftentimes inadvertently energizes the frog solenoids intermittently in response to spurious noise arising from other radio sources. For example, the radio control boards have proven too sensitive to the transmitted signals emanating from other nearby trolley vehicle transmitters and/or too susceptible to the harmonics of those transmitted signals. Such "false tripping" as it is called, if it occurs while a trolley vehicle is passing through a junction, can cause the energy collector assembly to separate or "dewire" from the overhead power conduit. Dewiring at even low speeds can cause a significant amount of damage to the trolley pole switch, the affected energy collector assembly and the overhead catenary on which it rides.
Experience has shown that the power supply board of the prior art controller unit also has its shortcomings. The power supply board serves in part to step down the 450-770 dc voltage present on the power conduit to the 24 dc volt level required for operation of the radio control board. Because the circuitry on the prior art power supply board dissipates approximately 60 watts of heat in stepping down the voltage, the enclosure in which the prior art controller unit is housed requires vents. Though some heat is carried away by air flowing through the vents, moisture suspended in the air tends to condense on the circuitry. The heat and moisture have been shown to promote oxidation of componentry on the controller unit and affect adversely its operation.
Referring again to those certain prior art controller units that include only a radio control board and the accompanying power supply circuitry, experience has shown that the circuitry on those radio boards and the power supply circuitry are oftentimes damaged by surge voltages arising on the trolley line. These surge voltages are passed to the prior art radio control board via the high voltage capacity mechanical relays to which the prior art radio board directly connects.
The radio control boards of the prior art controller units have also proven quite vulnerable to cold temperatures. Heating elements or insulation have been used to assure proper operation in cold weather climates. Other disadvantages relate to the reliability, the size, and the cost of the mechanical elements used in the prior art controller unit.
In a presently preferred embodiment, the present invention is intended primarily as a replacement for the prior art radio board contained within those certain prior art controller units that include only a radio control board and the accompanying power supply circuitry. In a second embodiment, the present invention may be also be used as a replacement for the signal processing unit described and claimed in the aforementioned application entitled Electronic Controller For A Trolley Pole Switch Mechanism.
The present invention constitutes an advance over prior art radio boards in several respects. First, the instant invention more accurately and selectively discriminates the modulated signals received from the trolley vehicle transmitters from the unwanted noise. This eliminates false tripping of the frog solenoids caused by prior art radio boards picking up signals from sources other than the intended trolley vehicle. Second, the instant invention also features a fine tuning adjustment that permits a technician to set the receiving range and sensitivity of the device to accommodate variations in field conditions. Third, the instant invention more reliably controls the power received from the power supply circuitry remaining on the prior art controller unit so as to supply the present invention with a protected and regulated source of power to operate same. Fourth, the instant invention operates dependably over a wide range of temperatures without need of heating elements or thermal insulation. These and other advantages favor the present invention over prior art radio boards in terms of cost, space and reliability.
It should be noted that the foregoing background information is provided to assist the reader in understanding the instant invention and any terms of art used herein are not intended to be limited to any specific meaning unless specifically stated otherwise in this specification including the following detailed description.